In
organic chemistry, a
heteroatom (from
Ancient Greek heteros, different, +
atomos) is any
atom that is not
carbon or
hydrogen. Usually, the term is used to indicate that non-carbon atoms have replaced carbon in the backbone of the molecular structure. Typical heteroatoms are
nitrogen,
oxygen,
sulphur,
phosphorus,
chlorine,
bromine, and
iodine.